Grain crops need to complete the process of remobilizing nutrients from the leaves to the grain at the end of the season in order to realize their grain yield potential. Delayed or slow remobilization will result in yield loss. In addition, grain moisture needs to reach a level that is low enough in order to be harvestable. Speeding up the entire process of remobilization (leaf senescence) and grain moisture dry down are not only important agronomic traits for high yield but also valuable to shorten the maturity of crops.
A maize gene, having similarity to a homeodomain-leucine zipper I-class homeobox gene was cloned and transgenic constructs were created to down regulate its endogenous expression in maize. The transgenic maize plants exhibited faster leaf senescence (remobilization) and quicker ear dry down than the non-transgenic control. Such a transgene effect may be used to speed up nitrogen/nutrients remobilization and grain moisture dry down process. Therefore the described gene can be used to improve N use efficiency, increase grain yield and shorten crop maturity.